| (* | |
| * BatEnum - Enumeration over abstract collection of elements. | |
| * Copyright (C) 2003 Nicolas Cannasse | |
| * 2009 David Rajchenbach-Teller, LIFO, Universite d'Orleans | |
| * | |
| * This library is free software; you can redistribute it and/or | |
| * modify it under the terms of the GNU Lesser General Public | |
| * License as published by the Free Software Foundation; either | |
| * version 2.1 of the License, or (at your option) any later version, | |
| * with the special exception on linking described in file LICENSE. |
| (* batList.ml *) | |
| type 'a mut_list = { | |
| hd: 'a; | |
| mutable tl: 'a list | |
| } | |
| external inj : 'a mut_list -> 'a list = "%identity" | |
| let map f = function |
| -- GHC/Base.lhs | |
| map _ [] = [] | |
| map f (x:xs) = f x : map f xs |
| import Data.Vector.Generic | |
| import qualified Data.Vector.Generic.Mutable as M | |
| iqsort :: (Vector v a, Ord a) => v a -> v a | |
| iqsort = modify go where | |
| go xs | len < 2 = return () | |
| | otherwise = do | |
| p <- xs `M.read` (len `div` 2) | |
| m <- M.unstablePartition (< p) xs | |
| go $ M.slice 0 m xs |
| $s$wfoldlM'_loop_s1qP = | |
| \ (sc_s1qv :: GHC.Prim.Int#) | |
| (sc1_s1qw :: GHC.Prim.Int#) | |
| (sc2_s1qx :: GHC.Prim.Double#) -> | |
| case GHC.Prim.>=# sc1_s1qw ipv1_s1a1 of _ { | |
| GHC.Bool.False -> | |
| case GHC.Prim.>=# sc_s1qv ipv4_s1fy of _ { | |
| GHC.Bool.False -> | |
| $s$wfoldlM'_loop_s1qP | |
| (GHC.Prim.+# sc_s1qv 1) |
Ответ на вопрос в этом посте.
Для начала слегка модифицируем код, чтоб он компилировался.
import qualified Data.List.Stream as S
import qualified Data.Vector.Unboxed as U
f n = let arr = U.enumFromTo 1 n
in S.sum $ S.map (\i -> arr U.! (i `rem` n)) $ S.unfoldr (\i -> if i < n then Just (i, i+1) else Nothing) 0
| {-# LANGUAGE ScopedTypeVariables #-} | |
| foo :: forall a. Eq a => [a] -> Bool | |
| foo (x:y:_) = x == y | |
| foo [_] = foo ([] :: [a]) | |
| foo [] = False |
| class Functor f where | |
| type C f a :: Constraint | |
| type C f a = () | |
| fmap :: (C f a, C f b) => (a -> b) -> f a -> f b | |
| -- Инстансы для "неограниченных" функторов остались без изменений: | |
| instance Functor [] where | |
| fmap = map | |
| instance Functor Set where |
| foo :: Eq a => [a] -> Bool | |
| foo (x:y:_) = x == y | |
| foo [_] = foo ([] :: [a]) | |
| foo [] = False |